Cisco Cisco Unified SIP Proxy Guida Alla Risoluzione Dei Problemi
in−network Net−CUCM
method INVITE
end sequence
sequence 2
in−network Net−PSTN
local−port 5060
end sequence
end trigger condition
Routing Lookup Policy
This section describes the routing lookup policy for the CUSP call processing flow.
Each routing policy is expressed as a sequence of steps and each is specified in order to perform a
lookup in a table.
lookup in a table.
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CUSP executes each step in order:
Each step has a selectable key.
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If the step produces a route, that route is used.
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If the step results in a "no−match," the next step is attempted.
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An SIP request can be routed to a single destination or to a Route Group (RG).
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The policy has Multi−layer Route Advance within a RG, and has configurable failover SIP response
codes.
codes.
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Policy−based request rejection is incorporated (4xx responses and above).
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Nested policies are allowed.
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Table−based routing is used, which has these properties:
It supports a large number of routes in a table (10,000+).
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Routes in a table are populated via CLI or a route file.
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Lookup keys are used, such as calling and called party number, carrier codes, and location
routing numbers.
routing numbers.
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Flexible rule matching is used, such as "longest prefix matching."
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Normalization Policy
This section describes the CUSP call processing flow normalization policy.
SIP headers are normalized based on a configured policy.
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Normalization involves the addition, modification, and removal of SIP headers.
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It is applicable to both SIP requests and responses.
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It is used in order to solve incompatibilities or interoperation issues between different SIP servers.
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It can be performed before or after routing logic is executed (Pre−Normalization and
Post−Normalization).
Post−Normalization).
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Normalization logic:
Normalization Policy − Defines what changes must be made to the SIP message.
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Normalization Triggers − Define how a normalization policy is chosen.
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The policy consists of steps, and each step specifies a single change to the SIP message. For example:
Number normalization
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TEL/SIP conversions
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Domain conversions
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Regular−expression processing
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Here is a flow chart that shows the process: